Radio shielding means



March 5, 1946. w. .1. SPENGLER ETAL 2,396,060

RADIO SHIELDING MEANS Filed May l, 1939 3 Sheets-Shea?I l T INVEMORS M ad ATTORNEY.

March 5, 1946. w. J: r.='ENGLER am 2,396,060

RADIO SHIELDING MEANS 5 Sheets-Sheetv 2 l Filed May `l, 1959 INVQTORS (www M ATTORNEY.

March 5, 1946.

W. J. SPENGLER ETAL RADIO SHIELDING MEANS 3 sheets-sheet 5 Filed May vl, 1959 INVQIATORS ATTORNEY.

im f wwf Patented Mar. 5,1946w RADIO SHIELDING MEANS Walter J. Spengler, Tullio Tognola, and Jakob B.

Frei, Sidney, N. Y., assignors tion Corporation, South Bend,

tion of Delaware to Bendix Avia- Ind., a corpora- Application May 1, 1939, Serial No. 271,220 7 Claims. (Cl. 174-72) This invention relates to ignition apparatus and more particularly to radio shielding means for electrical apparatus, such as the ignition system of an internal combustion engine or the like, and methods of making the same.

One of the objects of the present invention is to provide novel radio shielding means for igni- Still another object is to provide a novelly con.

structed radio shielding harness for the ignition distribution system of an internal combustion engine.

A further object is to provide a novel method Afor constructing a radio shielding harness of the above type. l

A still iurtherpbject is to provide a novel radio shielding harness for ignition conductors which is so constructed that said conductorsy may be readily installed therein without danger of damaging the insulation on said conductors.

Another object is to provide novel radio shielding apparatus for ignition conductors which is so constructed as to obviate the entrance and accumulation of moisture therein and to eliminate insulation failures.

Another object is to provide a novel radio shielding harness wherein the shielded ignition conductorswill not be chafed vor adversely affected in any way by reason of the vibration of the engine on which the harness is installed.

Still another object is to provide a radio shielding harness for an ignition distribution system having novel means associated with the manifold thereof for electrically connecting conductors in the manifold to detachable shielded conductors.

The above and further objectsand novel features of the invention will more fully appear fromv the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended to define the limits of the invention, reference for this latter purpose being had primarily to the appended claims.

In the drawings wherein like reference characters refer to like parts throughout the several views,

Fig. l is an elevation view, partly in section and with parts broken away, illustrating one form of shielding harness comprehended by the present invention;

Fig. 2 is a detail sectional view taken on line 2-2 of Fig. 1 and showing a socket connection associated with the harness manifold;

Fig. 3 is a detail sectional view taken on 3`3 oiFig.1;

Fig. 4 is a sectional elevation view of one form of the insulating sleeve which may be used in carrying out the invention, the section being taken on line 4-4 oi Fig. 5;

Fig. 5 is an elevation view of said insulating sleeve as viewed from the left in Fig. t; Y

Fig. 6 is a side elevation, partly in section and with partsbroken away, showing the harness of Fig. 1 connected to amagneto distributor shield;

Fig. 7 is a detail sectional View, with parts bro- .ken away, illustrating the shielding connections between the manifold and distributor shield;

Fig. 8 is a side elevation, partly in section and with parts broken away, illustrating one manner of connecting a portion of the shielding harness to a spark plug;

Fig. 9 is a view similar to Fig. 2 showing the socket plugged asm'i't is during the operation of lling the manifold;

Fig. l() is an elevation view illustrating a second embodiment oi the invention;

Fig. 1l is a side elevation oi the manifold of Fig. 10;

Fig. 12 is a detail sectional View taken substantially on line l-l of Fig. 10;

Fig. 13 is a detail view of a socket portion )A adapted for connection to the manifold tube of Fig. l0; and

Fig,A 14 is a sectional view taken on line lt-ld of Fig. 13.

Two embodiments of the invention are' illusv trated in the drawings, by way of example, in the form oi shielding harnesses adapted for use on modern radial aircraft engines, but it will be understood that the novel features of the invention may bedincorporated in shielding harnesses for other types and sizes of engines. Each form of harness shown comprises a metallic mani fold connected by shielding leads to the radio shields on one or more magnetos or ignition distributors and having a' plurality of outlets to which conduits for shielding individual conduc= tors leading to the engine spark plugs are detache ably connected. Each spark plug maybe connected to a distributor terminal by means of a continuous conductor but preferably the spark plug leads are detachably connected toseparate line` conductors in the manifold of the harness at the outlets in the latter and. if desired, those portions of the ignition conductors between the main manifold tube and the magneto distributor may also be readily detachable.

In harnesses heretofore provided much difficulty has been experienced in getting the insulated conductors into the manifold of the harness, particularly without chang the insulation thereonfat points where the conductors must be pulled around sharp metallic corners. vThis initial chailng of the insulation on the conductors has been a serious source of electrical loss due to corona, effect and of failures due to the ultimatecomplete breakdown'of the insulation. In the embodiment shown in Figs.- 1 to 8inelusive, there is provided a novel manifold for an ignition harness which may be readily and systematically wired without the slightest danger i 'of injury to' the insulation on the conductors.

fold comprises aring-like casting I5, the major portion of which is substantially channelor U-shaped in radial cross-section (Fig. 3). The open face of said casting is interrupted at suit,- ableintervals by integral cross pieces or lugs I6 to which suitable brackets Il are secured, thel latter serving as means for attaching the manifold to an engine (not shown). The openings between lugs I6 may be closed ,by removable plates I8 which may be either cast or stamped. The closure plates may be secured -to ring I5 by any suitable means, such as set screws I9 f which engage threaded bores in bosses 20 on the ring. In order to increase the strength and shielding properties of the assembled manifold, plates I8 are preferably provided with pilot portions 2| that closely t the openings of ring I5.

The latter and plates I8 are preferably cast from an aluminum alloy or other suitable light weight metal, thereby rendering it possible to provide relatively thick and strong wall sections without making theharness prohibitively heavy for aircraft use. Casting of the parts to proportion the wall thicknessess or provide strengthening ribs to meet with the strength requirements at particular points depending on the engine upon which the same is to be used. If desired, suitable gaskets may be employed between plates I8 and ring I5 to further insure against the entrance of moisture.

In most shielding harnesses of the continuous conductor type in use today on aircraft engines, one of the usual sources of failure is the burning of the insulation on the high tension conductors at or near the spark plugs. When the insulation on a single wire is burned or a single conductorV becomes otherwise defective it is usually necessary to remove the entire harness from the engine and often to `completely overhaul the harness to find and replace the damaged wire. Accordingly, the present invention provides novel shielded spark plug leads which are completely detachable from the manifold of the harness and the conductors therein.'

For the purpose oi' providing means whereby `makes it possible -lic conduit 32 and detachable electric and tween manifold I shielding connections be- IB and the spark plugs of an ,engine may be employed, the manifold' has a pluralityof outlet sockets combined therewith in As shown, each cylinder-like por as an integral pa and extending ra a n ovel maner for receiving a plug connector.

of said sockets comprises a tion 22 (Figs. 2 and 6) cast r1; of the closed face of ring I5 dially thereof. Socket portions 2 are each provided with an interioriy threaded opening 23 (Fig. 2

the interior of ring I 5, I8.

) and have communicationwith Preferably a hard metal bushing 24, which need not be removed during overhaul or inspection provided in opening of the harness, is 23 to thus prevent unnecessary'wear on the threads in -the soft metal of the manifold ring. Accordingly bushing 24 may be considered as 22 and, hence, as

recess 25 in the i an extension of socket portion a part of the manifold.

Slidably fitting into each bushing 24 and a nner wall of castingIS, 22 is a rigid electrical insulating sleeve or tube 26, said to provide v sleeve having a lportion thereofa cut away (Fig. 5) a rassage 21 for one ofthe plurality of insulated 'conductors 28 in the manifold (Fig. 2). ably rounded to sulation ductor extending The edges of opening 21 are preferobviate 'any chaiing of the :in-

on conductors 28 when the latter are pulled into the manifold. The` end of.each com into sleeve 26 extends partially and is held against withdrawal therefrom by a metallic washer or tip piece 29 secured a shoulder 30 in the bore of the sleeve.

to the conductor and engaging The outer end of sleeve 26 serves as a socket for receiving the unshielded insulated conductor 3I spark plug or other ignition For shielding bui-l insulated end of an leading to an engine device.

purposes, insulated wire 3| is surrounded, for the most part, by a exible metal- (Fig. 8). The en and are preferab a rigid metallic elbow 33 ds of the insulated wire or conshielding lead 32, 33 1y surrounded by rigid insulating spacer sleeves 34 and 35 (Figs. 2 and 8) adapted to slidab ly fit into socket 22, 2B and the shielding barrel 36 of a shielded spark plug 31.

Small coil springs 38 in any well-known manner make of conductors 3| and 39 secured to the ends electrical contact between said conductors and the central electrodes 40 of spark plugs 31 and manifold conductors 28, respectively, or, ifdesired, .said springs may be secured to electrodes 4I) and conductors 2 with conductors 3I.

8 for detachable contact 'Ihe ends of shielding conduit 32 are preferably detachably connected to manifold bushing 24 and elbow 33 by any suitable ymeans well-known in the art, such as by internally flanged cooperate with ex to said conduit (Fig. 2).

nuts 4I and 42 ternally flanged ferrules secured 33 is alsodetachably secured to spark plug barrel 36 in the usual manner by means of a flanged Fig. 8. l

Manifold I5. I8 may be connected to the con adjacent ends of elbow have telescopic relation ing conduits 4,1 having suilicient capacity to house a conductor for each cylinder of the engine. -In

the form shown, central rigidy tub tubes 49 and 50 each conduit 4l consists of a e 48 and twp'ilexible metallic which may be either detach- (Fig. 1) that The free end of elbow into the various parts into said shielded conduits 4l. Just as in the rst embodiment, the shielding and electrical connections between manifold 60, 6l and the spark plugs and the magneto or other source of current may either or both be detachable at .either or both ends thereof.

In order to iill manifold 60, 6i withinsulating compound, plugs 56 are placed in sockets 2B, 62 in the manner aboved described and outlets 64 are effectively sealed by means of flexible rubber grommets of a type vwell-known in the art. The conductors emerging from outlets 6d extend through a plurality of openings in the grommets and the latter are pressed into rm engagement with each one of the wires and the outlets by means of nuts engaging the grommet and threaded portions of the outlets in a manner well understoodin the art. Gaskets 65 may be provided between cap 58 and bushing 24 or socket portion 62, as the case may be, to insure an airtight connection. A source of v-acuum is then connected to tube 60 at one or more openings 66 in any suitable manner and the lling compound 55 in liquid form is drawn in by the suction through one or more openings 61; Because of the evacuation of the manifold the` filling compound seeksand fills all the vvoids around'conductors 28 and insulating sleeves 26, Preferably the liquid compound is allowed to settle for a short time and then baked to accelerate the drying thereof. Holes 66 and 61 may be closed with suitable plugs but this is not absolutely necessary. If desired the lling compound in liquid form may, be forced of the harness including the manifold tube and shielding leads by pressure means. The harness may be mounted on an engine by means of brackets 68 secured to ring 60.

Heretofore muchl difficulty has ,been experienced in preventing flash-overs from terminal 39 to a grounded portion of the spark plug or shield.. ing along a path between insulating sleeve 35 and insulating lining 361in spark plug barrel 36 (Fig. 8). Flash-overs of this character are facilitated by the accumulation ofmoisture on the engaging surfaces of said sleeve and lining or by moisture absorbed thereby and a series of ash-overs is effective to burn and ydestroy these insulating parts. The present invention comprehends novel means for obviating'the accumulation of moisture f on said parts and to prevent flash-overs of the above nature without altering the other characteristics and advantages of the shielded system novelly constructed manifold and wherein the current carrying conductors are prevented from rubbing against each other or against the shielding surrounding the same during the operation and, hence, vibrationy of the engine on which the harness is mounted. Novel means are also provided whereby one or a plurality of encased conductors may be molded in a matrix of insulating material which may be removed either manually or by means of a solvent without destroying the casing therefor, The novel shielding means provided is relatively inexpensive to manufacture and the upkeep thereof is considerably less than harnesses heretofore provided since the major portion thereof Will seldom if ever need to be overhauled.x The harness provided is also safe and dependable particularly since it is absolutely impervious to moisture of any nature whatsoever.

Although only two embodiments of the invention have been illustrated and described by way of example, it is to be expressly understood'that various changes might be made therein.` For example, the manifold sockets for receiving the spark plug leads may have an end rather than a side thereof secured to the manifold tube and yet embody certain features of the invention. Various other changes in the design and arrangement of parts illustrated and in the materials suggested may be made without departing from the spirit and scope of the invention,- as will now bef apparent to those skilled in fthe' art. For a definition of the limits of the invention, reference is had primarily to the appended claims What is claimed is: i

1. -A radio-shielding harness for the conductors of an ignition system comprising a rigid metallic manifold casing for enclosing and shielding? at least a portion of each of a plurality of ignition conductors, Yand a unitary mass of solid dielectric material' in a dry, non-moldable state substantially lling said casing around said conductors, said material being constituted by a dry reaction product of cashew-nut-shelhoil and formaldehyde. n

2. Shielding means for one or more electrical conductors comprising a metallic conduit having a continuous wall structure, and a lsolid ldielectric material filling said conduit around said conductors, said material being constituted by a dry reaction product of cashew-nut-shell oil and a drying agent.

or parts thereof. Said means are constituted by a thin film cinch-hardening moisture repellant (not shown), having the consistency of a heavy grease, spread over the outer surface of sleeve 35 before the same is inserted into its socket. This insulating material subinsulating material stantially lls the very small space between the sleeve and lining 36 and functions to exclude moisture from the surfaces thereof and to prevent crcepage of high tension sparks along said surfaces. One insulating material which has been found suitable is known commercially as "Tite Seal, and consists of a mixture of castor oil and mica powder. Sleeves 34 (Fig. 2) maybe similarly covered with said insulating .material if desired.

There is thus provided novel means adapted for use in shielding the ignition distribution system of an internal combustion engine and a novel method for assembling the various parts thereof.

A novel shielding harness is provided wherein thespark plug leads are Wholly detachable from a 3. In a shielding harness, a metallic manifold casing for enclosing and shielding an electrical conductor, and a dry flexible dielectric filling said casing around said conductor, said dielectric being constituted by a solid reaction product of liquid' cashew-nut-shell oil and formaldehyde.

4. 'I'he method of making a radio shielding harness which includes the steps of making a metallic casing, placing one or more electrical conductors therein, evacuating said casing,`intro ducing a mixture comprising Cashew-nut-shell oil and formaldehyde in liquid form into said casing around said conductors, and permitting said mixture to solidify.

5. In a radio shielded ignition system, a metallic casing, an electrical conductor having a, terminal in said casing, an insulating sleeve surrounding sald terminal and extending beyond the same, a second electrical conductor extending into said s1eeve,`a second insulating sleeve surrounding said second conductor in said iirstnamed sleeve. and a lm of non-hardening insulating material of a plastic nature interposed between said sleeves.

6. In a radio-shielding harness for the insulated conductors of an ignition system of an internal combustion engine, a rigid metallic manifold casing containing and shielding at least a portion of each of a plurality of insulated conductors. radio-shielding means extending from said casing to the spark plugs of said engine for connecting the conductors in said casing to said spark plugs,I and a yieldable solid dielectric material in a dry, non-moldable state substantially filling the space in said casing around said insulated conductors, said material being constituted by a reaction product o! polymerized Cashew-nut-shell oil and formaldehyde.

7. A radio-shielding harness for the conductors of an ignition distribution system of an interna! combustion engine comprising a rigid metallic manifold conduit containing and shielding at least a portion of each of a plurality of insulated ignition conductors, a plurality of flexible radio-shielding conduits extending from said manifold conduit to the spark plugs of said engine, each of said nexible conduits containing at least a portion of an insulated conductor and a dry reaction product of polymerized cashew-nutshell oil and formaldehyde substantially filling the remainder of the space therein for positioning and supporting the conductor or conductors surrounded thereby.

WALTER J. SPENGLER. TULLIO TOGNOLA. JAKOB R.. FREI. 

